Rheostat



July 15 1924 3 S. R. HIPPLE RHEOSTAT Filed Dec. 5,192 2 Patented July 15;, 1924.

UNITED STATES PATENT OFFICE.

SOLOMON BITTER HIPPLE, OF WILLIAMSIORT, PENNSYLVANIA, ASSIGNOR TO DX INSTRUMENT COMPANY, OF HARRISBURG, PENNSYLVANIA, A CORPORATION OF DELAWARE.

RHEOSTAT.

mama... filed December 5, 1922. Serial No. 605,048.

To all whom it may concern:

Be it known that I, SoLoMoN BITTER HIPPLE, a citizen of the United States, residing at Williamsport, in the county of Lycoming and State of Pennsylvania, have invented certain new and useful Improvements in Rheostats; andI do hereby declare the following'to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

Thisinvention relates to improvements in rheostats of that type in which a compressible conductive medium is interposed in the circuit to be controlled, means being provided for varying the compression of the medium to vary the resistance thereof. It has for its object the provision of a device in which a very delicate regulation of the compression of the resistance medium can be obtained that particularly adapts the device to radio installations.

In carrying out the in'vention, a compressible resistance medium is placed in an insulating container, between two coiled springs of different strengths, mounted in the opposite ends of the container, the springs and the interposed resistance medium bein adapted to be compressed to an; de sirecI extent by means of a regulable a justing means, preferably in the form of a screw, threaded into one end of the container and cooperating with the proximate spring. Owing to the differential strengths of the respective springs, a lar e element of the compressive force applied y. the adjustin screw will be taken up by the weaker of t 0 two springs, and the remainder of the force will be effected in compressing the resistance medium. If the compressive action of the screw be continued, the resistance medium is still further compressed until it offers sufficient opposition to cause the stronger spring to take up its .proper proportion of the force, so that, when the maximum stage of compression is reached, both springs are practically collapsed. During the compressive action applied by the a justing screw and the cooperating difi'erential springs, the compressive force exerted on the resistance medlum may be varied to the minutest degree, thereby varying the resistance to the flow of current proportionately, which admirably adapts the device to radio systems larly fine adjustment of resistance is essential.

Inthe drawings, Fig. 1 shows a sectional I view of one structural embodiment of the invention, and

Fig. 2 shows a similar view of another structural embodiment.

Referring to the drawings, more particularly to Fig. 1 thereof, 5 designates a cylindrical container of lava, or other suitable non-conductive material, closed at one end and open at the other. Threaded in the open end of the container is the metal plug 6 having a reduced extension 7. In mounting the rheostat the extension 7 is placed in an opening 8 of the panel 9 and a nut 10 turned onto this extension against the outer face of the panel clamps the rheostat in place. The extension also forms a binding post and by a second nut 11 thereon an end of the wire conductor (not shown) can be attached thereto. Seated in the closed end of the container is a screw 12 which, with the nuts 13, forms the other binding post for the wire conductor. 1

Threaded through the extension 7 andthe body part of the plug 6 is the adjusting screw 14 with a thread of very small pitch. On the outer end of the screw is the hard rubber or fibre hand-wheel 15 for turnin the same. In one end of the container, .a jacent to the inner end of the adjusting screw 14, is the comparatively strong spring 19 are thesopposite fibre disks or washers 20 and 21' respectively and between these disks is the resistance medium 22 of granular conducting material, such as comminuted carbonor a mixture of such carbon and suitable granular metal. The disks 20 and 21 fit the bore of the container closely so asto confine the granular material between them and both disks have a central opening so that the granular material can make an of fective electric contact through the disks with the metal caps 18 and 19 adjacent to said disks. The metal caps 18, 18 and 19 fit the bore of the container. rather loosely so that they can easily move therein. The

springs 16 and 17 are normally under tension and exert opposing forces against the opposite ends of the resistance medium 22 and thecompression so exerted normally tends to-pack the material more or less and its conductivity or resistance is effected thereby. By turning the adjusting screw 14 the compression of the resistance medium can be regulated.

In the operation of the device, the terminals of the conductor, of which it is desired to regulate the resistance, are attached to the binding posts provided by the extension 7 and the nuts 10-11 and by the screw 12and "nuts 13. In this way the circuit is established between the terminals of the conductor, through the extension 7 the plug 6, the screw 14:, the cap 18, the comparatively strong spring 16, the cap 18, the resistance medium 22, the cap 19, the comparatively weak spring 17, the cap 19' and the screw 12. Should it be desired to vary the resistance of the conductor, to lessen it for an instance, the screw 14. is turned into the container, thereby applying a compressive force to the springs 16 and 17 and the interposed resistance medium. During the initial part of the compression there will be hardly any deformation of the stronger spring, but the Weaker spring will be deformed to some extent and the remainder of the energy will be applied in compressing the resistance medium. A slight inward adjustment of the regulating screw will result in a very slight compressive action on the resistance medium; consequently, a Very delicate adjustment of the compression in the resistance medium may be effected, which is very desirable in radio work.

The structural embodiment of the invention shown in Fig. 2 is quite similar to that shown in Fig. 1. 'In the second structural form the resistance medium 22 is formed by a pile of disks of carbon or other suitable material. By regulating the compression of this pile, as in the granular formation, the resistance of the medium can be varied. In the second form the fibre disks 21 of the first form are eliminated as the carbon disks of the pile need no confinement and can bear directly on the metal caps 18 and"19. Also, in the second form the metal plug 6' has a binding post formed by an inwardly turned lip 7' and holding screw 11. In other respects the second structural form isfthe same as the first and operated in the same way.

What I claim is:

1. A rheostat comprising an insulating casing, differential springs in the opposite ends of said casing, a compressible resistwith said screw and the spring in the remote the differential action of the springs.

3. A rheostat comprising an insulating casing, a body of compressible resistance material therein, differential springs in opposite ends of the casing between which said material is confined, an adjusting screw mounted in one end of said casing cooperating with the adjacent spring for applying accurately regulated pressure to the resistance medium through the differential action of the springs, and line terminals connected end of thecasing. I

4. A rheostat comprising an insulating casing, a binding post in one end of the easing, a plug in. the opposite end thereof, differential springs in the opposite ends of the casing, conducting disks engaging the inner ends of the springs, a compressible resistance medium confined between said disks, and an adjusting screw threaded through said plug cooperating with the adjacent spring for applying accurately regulated pressure to the resistance medium through the differential action of the sprin s.

5. rheostat comprising an insulating m casing, difierential springs in the opposite ends of the container, metal caps on the inner ends of the springs, a compressible resistance medium in the container between said caps, and regulative means for applying pressure to the springs and the interposed resistance medium.

6. A rheostat comprising an insulating casing, differential springs in the opposite ends of the container, a granular resistance medium in the container between said springs, washers in the container between the ends of the springs and the adjacent resistance medium to hold the granular material in place, and regulative means for applying pressure to the springs and the interposed resistance medium.

7. In a rheostat of the compression type, the combination of a cylindrical container formed of insulatin material, springs in 1 the opposite ends 0% the container, metal caps on the inner ends of the springs, a granular resistance medium in the container between said caps, washers in the container between the'caps and the adjacent resistance medium to hold the granular material in place, said washers having openings to permit electrical contact between the adjacent caps and the granular material of the resistance medium, and regulative means for applying pressure to the springs and the interposed resistance medium.

8. In a rheostat of the compression type, the combination of a cylindrical container formed of insulating material closed at one end and open at the other, a metal plug seated in the open end of the container and having a threaded extension provided with clamping nuts to attach thereto a wire ter- 15 minal and to attach the rheostat to a supto connect a wire terminal thereto, a resistance'medium in the container between the springs, and a regulating screw threaded through said plug and operative to compress the springs and the interposed resistance medium.

In testimony whereof I aflix my signature.

SOLOMON BITTER HIPPLE. 

